GB2194446A

GB2194446A - Wound dressing

Info

Publication number: GB2194446A
Application number: GB08719632A
Authority: GB
Inventors: Patrick Lewis Blott
Original assignee: Smith and Nephew Associated Companies PLC
Current assignee: Smith and Nephew PLC
Priority date: 1986-08-20
Filing date: 1987-08-19
Publication date: 1988-03-09
Anticipated expiration: 2007-08-19
Also published as: ZA876101B; ATE106710T1; GB2194446B; DE3789998D1; IE61186B1; EP0256893A3; EP0256893B1; AU7719087A; GB8719632D0; ES2054680T3; EP0256893A2; AU601471B2; IE872175L; GB8620227D0; JPS6351865A; CA1323268C; JP2513712B2; DE3789998T2; US4990144A

Abstract

A non-adherent wound dressing (1) comprising a film (2) which contains depressions (3) over the wound contacting area of the dressing is described. The depressions contain a viscous pharmaceutical composition which is suitable for topical application to the skin and which preferably contains from 1 to 12.5% by weight of antibacterial agent. In a preferred form of the dressing each depression has an aperture at its apex whereby transmission of wound exudate through the dressing to an absorbent placed on the non-wound contacting surface of the dressing is permitted while at the same time the pharmaceutical composition may release it medicament to the environment of the wound.

Description

GB2194446A 1 SPECIFICATION of the present invention will contain within

the depressions a pharmaceutically acceptable car Wound dressing its preparation and use rier containing medicament.

The medicament present in the pharmaceuti- The present invention relates to low adher- 70 cally acceptable carrier may be any one of ency wound dressings which may contain a those which may be topically applied to the medicament suitable for topical application to skin including, steroids, debriding agents, wounds, to their preparation and use. wound healing promoters, local anaesthetics, Dressings which consist of a medicated antibacterial agents, antibiotics and the like.

ointment impregnated open-work support such 75 Preferably the medicament will comprise anti as tulle gras have been used for many years bacterial agent. Suitable antibacterial agents in for dressing wounds,see for example United clude iodophors such as polyvinyl pyrrolidone Kingdom Patent No. 1090421 and 1599159. iodine, chlorhexidine and its salts such as the A disadvantage which is found with this type diacetate, digluconate and dihydrochloride, sil of dressing is that the healing wound may, 80 ver compounds such as silver sulphadiazine or despite the presence of an ointment, grow may comprise an admixture of two or more into the tulle gras and which therefore cannot compatible antibacterial agents.

be removed without retraurnatising the wound. The amount of medicament which is applied European Patent Application No. 171268 topically may be regulated by its concentration discloses an absorbent dressing comprising a 85 in the carrier and by the frequency and dimen bag formed from a film containing apertured sions of the depressions which hold the car depressions and holding pieces of foam. The rier.

construction of the film is such as to prevent The carrier will contain a therapeutically ef- re-emergence of any absorbed exudate from fective amount of medicament. Thus for the dressing. This advantageous property also 90 example in a preferred embodiment the carrier retards the release of medicament which may will comprise an ointment containing antibac be present within the bag. terial agent at a concentration of, for example, I have now found that by using a dressing 1 to 12.5% by weight based on the weight of which employs a film containing depressions the carrier.

in which the depressions are substantially full 95 In one embodiment the film which contains of a medicated viscous pharmaceutical carrier the depressions is continuous, that is does the above disadvantages may be mitigated. It not contain apertures. Aptly the film maybe is a feature of the prior art dressings that then formed from a material which has a unimpeded transmission of exudate through moisture vapour transmission rate (MVTR) of the dressing to an absorbent element is per- 100 greater than 250g/M2/24h at 37C and 100% mitted. The fact that my dressing satisfactorily to 10% relative humidity difference, more transmits exudate is suprising since the pro- suitably greater than 500 g/M2/24h and most gress of exudate would seem to be impeded suitably greater than 1000g/M2/24h when by the presence of the viscous carrier which measured using the Payne Cup Method. In fills the depressions and covers the apertures. 105 such dressings the normal perspiration of the The dressings of the present invention further skin will evaporate through the film and so show a low propensity to adhere to the avoid causing maceration to the underlying wound and effectively release the medicament skin.

from the carrier and also may provide a met- The depressions containing the apertures ered dose and a metered release rate of the 110 may be arranged in a pattern within the bor medicament which is not obtainable when us- ders of the film comprising the dressing. For ing medicated carriers alone. example, a square dressing of 10cm X 10cm A dressing comprising a film containing de- might comprise a central portion of 5cm x pressions has the added advantage that differ- 5cm in which the depressions contain aper ent types of pharmaceutically acceptable carri115 tures surrounded by a border 2.5cm wide of ers may be held within the depressions flat film or of a film containing unapertured whereby more than one medicament may be depressions. Alternatively a strip of apertured released to the skin surface. Antibacterial depressions may extend across the width of agents are particularly suitable for use in this the dressing leaving a flat film or a film con dressing. 120 taining unapertured depressions on two oppo- Accordingly the present invention provides a site sides, non-adherent wound dressing comprising a The film used in the dressings of the pre- film which contains depressions over the oper- sent invention may be considered to have de ative area of the dressing and contained pressions impressed out of the plane of the within the depressions a viscous pharmaceuti- 125 film over the operative area of the dressing.

cally acceptable carrier. Suitably each depression may contain at least The operative area of the dressing is that one aperture within its walls, however, it is area which covers the wound and the area of preferred if each depression has a single aper skin adjacent to the wound. ture which may be formed for example by the However, it is preferred that the dressings 130 removal of the apex of the depression during 2 GB 2 194 4,46A 2 the manufacturing step. ing or dispensing quickly enough to cope with The use of a film containing apertured de- the evolution of exudate.

pressions is further preferred because it is ob- The dressings of the present invention may seved that exudate flows more freely to any have adhesive coated handles along at least absorbent pad used in conjunction with the 70 one of their edges for the purpose of adhering dressing through the apertures thereby reduc- the dressing to the skin. Suitably the dress ing risk of trapping exudate beneath the ings have adhesive coated handles on two op dressing. It is also observed that dispersal of posed edges. One advantage of using adhe the medicated carrier from the depressions is sive coated handles is that during the applica also facilitated. 75 tion of the dressing a handle may be adhered However, in a favoured embodiment at least to the skin to stabilise the dressing and then a portion of the depressions may each contain a second or other handles may be adhered to one or more apertures. Here the film may be the skin so that during wear any tendency for formed, for example from a film which has a the dressing to move relative to the surface of low moisture vapour transmission rate as such 80 the wound is reduced. Suitable handles and films have been observed to have an even the material from which they may be made lower propensity to adhere to the wound than are described in European Patent Application have the previously mentioned moisture va- No 161865. - pour permeable films. Aptly the dressings of the present invention Thus in a favoured aspect the present in- 85 are sterile and are packaged in bacteria-proof, vention provides a non-adherent wound dress- water-proof pouches until required. The dress ing comprising a film which contains a pattern ings may be sealed into the pouch and steril of depressions therein over the operative area ised by conventional methods.

of the dressing and wherein at least a portion Alternatively the components of the dress- of the depressions each contain one or more 90 ing may be made separately in a sterile condi apertures and contained within the depres- tion and assembled under sterile conditions sions a viscous pharmaceutically acceptable and then sealed into a pre- sterilised bacteria carrier. proof, water-proof pouch. Suitable pouches in- The film containing the depression may be clude one available as 's b w' View Pack considered to have a thickness defined as the 95 (Trade Mark) and vacuum formed styrene perpendicular distance between the tip of the trays with foil or styrene lids.

depression or the aperture and the plane of The pharmaceutically acceptable carrier may the film. be bland that is it may not contain any medi- Suitably the film will have a thickness as cament, for example, it may comprise an hereinbefore defined of from 0.1 to 3 mm, 100 emollient cream but preferably the carrier will more suitably 0.75 to 2 mm and preferably contain medicament.

1.0 to 1.5 mm. The pharmaceutically acceptable carrier is When apertures are present then suitably present in individual depressions within the the apertures in the film will have an area film. It is therefore possible to employ more equivalent to a circle diameter 0.25mm to 105 than one carrier to carry more than one medi 1.5mm and preferably 0.3 to 1.0mm. The cament in a single dressing. The carriers may open area of the apertured film may suitably be spread in a pattern so that the two carriers be between 1 and 25% and more suitably 10 are mutually non-overlapping. Alternatively two and 25%. medicaments could be combined in one car- A contribution to the low adherency shown 110 rier. It is also possible to contain one medicaby the dressings of 1he present invention is ment within two different carriers which pro believed to be due to the small land area be- vided different release rates for the medica tween the depressions. This land area is the ment, for example one carrier may give rapid area in the operative area of the dressing release and one may give sustained release.

which may contact the skin when the dressing 115 A film containing depressions but not aper- is in place. Suitably the land area may comtures may be prepared by plating a strip of prise 5 to 10% of the surface of the film the film onto an embossed film of polypropyl containing the depressions. ene having a regular pattern of embossments.

Suitably the number of depressions per sq. The two films are passed in contact between cm may be in the range from 4 to 30 per sq. 120 the nip of two rollers under pressure. The cm, more suitably will be from 5 to 20 per rollers comprise a silicone rubber coated roller sq. cm and: preferably 6 to 12 per sq. cm. and a metal roller heated to elevated tempera- Suitably the ratio of the land area to the ture, for example 80 to 100'C, depending area of the depressions may be in the range upon the nature of the film. The film is re 1:20 to 1:9. 125 trieved as a film containing depressions im- The land area may also contain apertures. pressed out of the plane of the film. The film These apertures may be suitably from 0. 1 to may be made from an ethylene- vinyl acetate 1.0 mm and may facilitate the flow of wound copolymer-styrene incompatible blend or from exudate from a heavily exuding wound or moisture vapour permeable material such as a where the ointment is not capable of dissolv- 130 hydrophilic polymer for example a hydrophilic 3 GB2194446A 3 polyurethane. The depressions are filled by the carrier in the A film containing apertures in the depres- method hereinafter described and a release sions may be prepared by placing a polymer paper placed over the carrier.

film on to the embossed surface of a thermo- The medicament when in the dressings of plastic polymeric film. The embossments are 70 the present invention may be in the form of a suitably arranged in a pattern and are in the pharmaceutical composition which is suitable form of discrete, raised areas with troughs be- for topical treatment of skin or wounds for tween them. The embossment may be any example treatment of burns, ulcers and other shape including square truncated pyramidal,- skin lesions exposed to the risk of infection.

hexagonal, conical or hemispherical. A film of 75 Suitable forms of the topical composition of polyethylene is placed over the polymer film this invention include ointments, gels, oily sus urging it against the embossments. The three pensions, emulsions, lotions, pastes, powders layered sandwich is then subjected to pres- and the like which are viscous enough to be sure at elevated temperature, for example retained in the depressions in the film.

80'C for a period of time. The temperature, 80 Preferably the composition will be in the pressure and time required for the process will form of an ointment and most preferably as a depend upon the properties of the polymer hydrophilic ointment such as an oil-in-water film but will be sufficient for the film to flow emulsion. Suitable bases are described in away from the tip of the embossment leaving Chapter 87 Ointments: Emulsion Bases in Re the tops of the embossments uncovered so 85 mingtons Pharmaceutical Sciences, 15th Ed.

forming the aperture in the depression in the 1975, pages 1532-34. Other suitable ointment film. The pressure and heat are discontinued bases include those described in British Patent and the polyethylene film is removed. The No.1240545.

apertures which are uppermost may be cov- A particularly suitable ointment base is ered by a sheet of polyester film which is 90 therefore an oil-in-water emulsion containing then adhered lightly to the film surrounding from 0 to 25% of petrolatum or liquid para the apertures by a heated iron. The film con- ffin, 2 to 20% of a fatty alcohol, 0 to 12% of taining the apertured depressions and poly- an emulsifying agent, up to 10% of non-ionic ester film may then be peeled from the em- surfactant and 5 to 25% of a polyhydric alco bossed thermoplastic polymeric film. The de95 hol and the balance to 100% being deionised pressions in the film may then be filled with or distilled water. Aptly the fatty alcohols are the medicament in its carrier. The emboss- those conventionally used in ointments and ments of the thermoplastic film may be pre- are water insoluble. Suitable alcohols include treated with a release compound to facilitate stearyl alcohol, cetyl alcohol, lauryl alcohol and release of the film containing the depressions. 100 myristyl alcohol. Suitably the emulsifying agent In a preferred form the film has geometrically is a glyceryl fatty acid ester and is preferably shaped depressions having approximately cir- glyceryl monostearate. Suitable non-ionic sur cular holes at their apex. factants include the polyoxyethylated sorbitan Polymeric material which is suitable for pre- fatty acid esters and sorbitan fatty acid est- paring films containing the depressions include 105 ers. An emulsifying wax may be used in place thermoplastic elastomeric polymers or polymer of both or part of both of the fatty alcohol blends. A favoured polymeric material is a and non-ionic surfactant. The polyhydric alco blend of an ethylene-vinyl acetate copolymer hol acts as a humectant and suitable alcohols and an incompatible polymer such as a polyo- include propylene glycol, sorbitol or glycerin or lefin and particularly polystyrene. A particularly 110 mixtures thereof.

preferred polymeric material is a blend of from An alternative ointment may contain one or to 90 parts by weight of ethylene-vinyl a mixture of polyalkylene glycols for example acetate copolymer and 60 to 10 parts by polyethylene glycol. Suitably the ointment may weight of polystyrene and more preferably 60 contain a mixture of a high molecular weight to 90 parts ethylene-vinyl acetate copolymer 115 polyethylene glycol and a low molecular and 40 to 10 parts polystyrene. If necessary weight polyethylene glycol.

the polymeric material may include fillers or The compositions used in the present inven- whitening materials such as titanium dioxide. tion may be in the form of an aqueous gel.

The film from which the film containing de- Suitable gelling agents include polyoxyethy- pressions is formed may suitably have a thicklene-polyoxypropylene diol block copolymers, ness of from 50,4m to 120ym and preferably polyacrylic acid lightly cross- linked with triallyl to 100,um. sucrose which has been neutralised using an In an alternative embodiment of the present alkali metal hydroxide, cellulosic derivatives invention the apertures in the depressions of such as carboxymethyl cellulose, hydroxyme the film may be covered by a polypropylene 125 thyl cellulose, natural gums and the like. A film which may be vacuum formed onto the preferred group of gelling agents are the poly apertured film whilst it is still in place on the oxyethylene- polyoxypropylene diol block co embossed polypropylene film. The apertured polymers which are commercially available as film and the polypropylene film may be peeled the Pluronics from BASF- Wyandotte. (Pluronic away from the polypropylene embossed film. 130 is a registered trade mark of BASF-Wyan- 4 GB2194446A 4 dotte). which comprises applying to the body of an Suitable gel forming block copolymers of animal a dressing as hereinbefore described.

polyoxyethylene-polyoxypropylene will have a Preferred embodiments of dressings of the molecular weight from 4,600 to 13,500 (ap- invention will now be described by way of proximately) and will be present in the gel in 70 example only and with reference to the draw an amount from 50% for the lower molecular ings in which weight copolymers to 20% for the higher Figure 1 shows a dressing comprising a molecular weight copolymers, so that the gel continuous film containing depressions within when applied topically is neither too stiff nor a boarder of flat film.

too fluid. Typically the gels are formed by 75 Figure 2 shows a crosssection through the mixing together the copolymer and water to dressing of Figure 1. 1 form an aqueous solution at a temperature of Figure 3 shows a dressing comprising a film 2'C and adding the medicament and then alcontaining square pyramidal depressions which lowing the solution to gel as it warms to am- are apertured.

bient temperature. Suitable Pluronics are those 80 Figure 4 shows a crosssection through a designated as F108, F127 and P105 ' portion of the dressing of Figure 3.

The composition used in the present inven- Figure 5 shows a dressing comprising a film tion may also be in the form of a hydrophobic containing conical depressions the inner rows ointment. Suitable hydrophobic ointments are which are apertured and the outer rows which those which are formed from white or yellow 85 are continuous.

soft paraffin or a mixture of such with liquid Figure 6 shows a crosssection through the paraffin. A preferred ointment base comprises dressing of Figure 5.

a mixture of.white soft paraffin and liquid pa- Figures 7 and 9 show a dressing comprising raffin in a ratio of 5:1 to 1:1. However, in a continuous film with alternative patterns of general terms aqueous based systems will be 90 depressions.

preferred. Figures 8 and 10 show a cross-section The hydrophobic ointment base may also through a portion of the dressings shown in contain non-ionic surfactants such as polyoxy- Figures 7 and 9 respectively.

ethylated sorbitan fatty acid esters and sorbi- Figures 11 and 12 show magnified portions tan fatty acid esters. The presence of non- 95 of dressings of the type shown in Figures 1 ionic surfactants increases the miscibility of and 5 respectively in which the land area be the ointment with wound fluid and aids re- tween the depressions contains apertures.

lease of the medicament. Suitably the non- The dressing illustrated in Figure 1 shows a ionic surfactant will be present in an amount dressing (1) formed from a continuous film (2) from 0.1 to 0.5%. Preferably the non-ionic 100 which contains a pattern of depressions (3) in surfactant is 0.1% of polyoxyethylene sorbitan the form of a strip which lies in the centre of triolate and 0.1% sorbitan monopalmitate. the dressing (1) and is the operative area of The pharmaceutically acceptable carrier may the dressing. The film is formed from a mois- be placed in the depressions in the film by ture vapour permeable material such as a spreading it over the: film using a doctor blade 105 polyurethane, for example an Estane (Trade and removing any excess. The carrier substan- mark), an elastomeric polyester, for example a tially fills the depressions and the polyester Hytrel (Trade mark) and a polyether-polyamide film or vacuum-formed polypropylene film for example a Pebax (Trade mark). A preferred covering the apertures prevents the pharma- film may be prepared from a hydrophilic poly ceutical composition passing through the aper- 110 mer such as a hydrophilic polyurethane which tures. The other side of the apertured film aptly contains from 20 to 40% by weight of may then be covered by a piece of paper or water when hydrated. Suitable hydrophilic po-.41 film which forms a protector during storage. In lyurethanes are described in United Kingdom use the dressing is removed from the pouch, Patent No 2093190B.

the protector is removed and the dressing 115 The film (4) which surrounds the depres- placed with the pharmaceutically acceptable sions (3) is flat and could carry a coating of a carrier against the skin. The polyester film or skin-compatible pressure sensitive adhesive for polypropylene film covering the apertures is adhering the dressing to the skin. The phar then removed. The dressing may be held in maceutically acceptable carrier is contained place by conventional bandage means. Aptly 120 within the depressions (3).

an absorbent pad may be placed over the Figure 2 shows a cross-section through the apertures to absorb any exudate which might dressing shown in Figure 1 along the line issue from the wound. 2-2. The figure shows the relatively small Aptly the dressings of the present invention amount of land area (5) between the depres- are sterile and are packaged in bacteria-proof, 125 sions (3). Only a small amount of this area (5) water-proof pouches until required. The dress- would contact the skin over the wound and ings may be sealed into the pouch and steril- hence the dressing shows low wound adher ised by conventional methods. ency.

In a further aspect therefore the present in- Figure 3 shows a second embodiment of a GB2194446A 5 Ing (6) comprises a film (7) which contains the weight of polymers). The film had a thick depressions (8) in the form of square ness of 75 to 100,um. A strip of the film was pyramids the apices of which have been re- placed on an embossed film of polypropylene moved during their preparation. In this em- having hexagonal bosses arranged so that bodiment the film is completely covered by 70 there are 10 embossments per sq.cm. (ap depressions. The pharmaceutically acceptable prox). The two films were passed in contact carrier (9) may be placed in any or all of the between the nip of two rollers under pressure, depressions (8). Prior to use the dressing is a silicone rubber coated roller and a metal sandwiched between two removable protector roller heated to 100'C with a silicone rubber layers (not shown) to prevent the carrier being 75 mat being in contact with the other side of ejected from the depressions for example dur- the blend film. A second pass was made be ing transportation or storage. The film is tween a silicone rubber roller and a metal rol suitably formed from a blend of ethylene-vinyl ler at 100'c to form the apertures, (if a non acetate copolymer and polystyrene. apertured film is required this second pass will Figure 4 shows a cross-section through a 80 be omitted), whereby the excess polymer portion of a dressing shown in Figure 3. The blend material from the apertures is removed depressions (8) are caused to contain aper- on the metal roller. The embossed apertured tures (10) by removing the apices of the polymer blend film was then removed from square pyramids in the forming process. The the polypropylene embossed film and then re pharmaceutically acceptable carrier (9) is 85 applied. A film of polyester was lightly ad placed in the depressions (8). The land area hered to the blend film over the apertures us (11) between the depressions (8) forms from ing pressure and heat. The embossed aper to 10% of the area of the film. tured film-polyester laminate was then reco- Figure 5 shows a third embodiment of a vered from the polypropylene embossed film dressing of the present invention. The dress- 90 to provide the laminate of embossed aper ing (12) comprises a film (13) which contains tured film containg depressions adhered to a a pattern of conical depressions (14). In this polyester film which contacted and covered dressing the two outer rows of the depres- the apertures of the film.

sions (14) are not apertured while the inner An ointment comprising 1% silver sulphadi- rows contain an aperture (15) formed by re- 95 azine in a hydrophilic ointment was spread moval of the apices of the cone during manu- over the polymer blend film dressing so that facture. the ointment entered into the depression. Any Figure 6 shows a cross-section through a excess ointment was removed by scraping the dressing shown in Figure 5 along the line 6-6. surface with a flat blade. The presence of the The outer two rows of depressions (14) are 100 polyester film prevents the ointment from run not apertured while the centre three rows are ning out through the apertures. The dressing apertured. may be covered by a second releaseable layer Figures 7 and 9 show dressings (16, 19) and packaged in a bacteria proof, water-proof which comprise a continuous film (17, 20) pack and sterilised by 2.5 Mrad gamma-irradi which has different types Of depressions (18, 105 ation.

21) impressed in the film.

Figures 8 and 10 show the corresponding Example 2 cross-section views of the dressings 7 and 9. A film was prepared by extruding a blend of Figure 11 shows q magnified section of the ethylene-vinyl acetate copolymer (90 parts by type of dressing shown in Figure 1 which 110 weight), high impact polystyrene (10 parts by comprises a dressing (22) formed from a conweight) and titanium dioxide (4% by weight of tinuous film (23) having depressions (24) im- the weight of polymers). The film had a thick pressed out of the plane of the film. The land ness of 80,um. A strip of the film was placed areas (25) contain small perforations (26) on an embossed film of polypropylene having which permit transmission of wound exudate 115 hexagonal embossment arranged so that there from heavily exuding wounds. are 10 embossments per sq.cm. The two Figure 12 shows a magnified section of the films were passed in contact between the nip type of dressing shown in Figure 5 which of two rollers under pressure, a silicone rub comprises a dressing (27) formed from a film ber coated roller and a metal roller heated to (28) having conical depressions (29) the outer 120 100'C. A rigid, plain film of polyethylene was rows (30) of which are not apertured and the then placed onto the polymer blend film and a inner rows (31) which are apertured. The land second pass was made between the nip of areas (32) contain apertures (33) close to the two metal rollers heated to 100'C. The film non-apertured depressions (30). sandwich was allowed to cool and the poly 125 ethylene film removed. A film of polyester Example 1 (Melinex, trade mark) was lightly adhered to A film was prepared by extruding a blend of the embossed film over the apertures using ethylene-vinyl acetate copolymer (80 parts by pressure and heat. The embossed polymer weight), high impact polystyrene (20 parts by blend film was then removed from the poly weight) and titanium dioxide (4% by weight of 130 ethylene embossed film, to provide a laminate 6 GB2194446A 6 of embossed polymer blend film adhered to a an oil-in-water composition containing silver polyester film which contacted and covered sulphadiazine is filled into the depressions and the apertures of the embossed film. covered by a removable protector. The dress- An ointment was prepared by mixing to- ing so formed may be placed in a vacuum gether polyethylene glycol 400 (70 parts by 70 formed styrene tray and covered with a foil lid weight), polyethylene glycol 4000 (20 parts and sterilised.

by weight) and polyvinyl pyrrolidone-iodine (10 parts by weight). Example 7 The ointment was spread over the polymer A dressing similar to that described in blend embossed film dressing so that the oint- 75 Example 6 is prepared except that the film ment was filled into the depressions. Any ex- used is a polyetherpolyester elastomer, Hytrel cess ointment was removed by scraping the 4056 and the composition comprises 10% surfacewith a flat blade. The presence of the polyvinyl pyrrolidone- iodine in a polyethylene polyester film prevents the ointment from run- glycol carrier.

ning out through the apertures. The dressing 80 may be covered by a second releasable layer Example 8 and packaged in a bacteria proof, water-proof A dressing similar to that describd in pack and sterilised by gamma-irradiation. Example 6 is prepared using a hydrophilic In use the dressing is removed from the polyurethane prepared in manner described in pack and the first release layer removed, the 85 Example 2 of United Kingdom Patent No.

dressing is then plated with the ointment 2093190B. The depressions are filled with a against the skin and the polyester film is re- hydrophobic ointment composition containing moved. An absorbent pad may be placed chlorhexidine digluconate and a surfactant.

onto the dressing in contact with the aper

Claims

tures. 90 CLAIMS

1. A non-adherent wound dressing compris- Example 3 ing a film which contains depressions over the A polymer blend film was embossed in a operative area of the dressing and contained similar manner to that described in Example 1. within the depressions a viscous pharmaceuti Instead of using a polyester film, a polypropyl- 95 cally acceptable carrier.

ene film was vacuum formed over the em- -

2. A wound dressing as claimed in claim 1 bossed film to cover the apertures. The lami- in which the pharmaceutically acceptable car nate could be peeled from the polyethylene rier contains a therapeutically effective amount embossed film because the polymer blend film of at least one medicament.

adhered more strongly to the polypropylene 100

3. A wound dressing as claimed in claim 2 than to the polyethylene. The ointment was in which the pharmaceutically acceptable car then filled into the depressions as before in rier contains from 1 to 12. 5% of antibacterial Example 1 and the dressing packaged and agent.

sterilised as previously.

4. A wound dressing as claimed in claim 3 In use the dressing was placed against the 105 in which the antibacterial agent comprises sil- skin and the vacuum formed polypropylene ver sulphadiazine.

peeled off.

5. A wound dressing as claimed in claim 3 in which the antibacterial agent comprises of Example 4 polyvinyl pyrrolidone-iodine.

A dressing similar to that described in 110

6. A wound dressing as claimed in claim 3 Example 1 was prepared except that the oint- in which the antibacterial agent comprises a ment was formed from an oil-in-water emulsalt of chlorhexidine.

sion containing silver sulphadiazine.

7. A wound dressing as claimed in claim 1 in which the film which contains the depres Example 5 115 sions is continuous and has a moisture vapour A dressing similar to that described in transmission rate of greater than 250gm-2 Example 1 was prepared except that the oint- 24h 2 at 37'C and 100% to 10% relative ment was formed from an oil-in-water emul- humidity difference.

sion containing chlorhexidine di gluconate or

8. A wound dressing as claimed in claim 1 chlorhexidine diacetate. 120 in which at least a portion of the depressions contain one or more apertures.

Example 6

9. A wound dressing as claimed in claim 1 A film of a thermoplastic polyurethane, Es- in which t he film contains a pattern of aper- tane 5714F, is placed against an embossed tured and continuous depressions.

film of polypropylene. The two films are 125

10. A wound dressing as claimed in claim 8 passed on contact between the nip of two in which the apertures have an area equivalent rollers under pressure and at an elevated tem- to a circle of diameter 0. 25mm to 1.5mm and perature. Depressions are formed in the poly- film has an open area of between 10 and urethane film without creating apertures. The 25%.

film is removed from the embossments and 130

11. A wound dressing as claimed in claim 1 7 GB2194446A 7 in which the land area between the depres sions comprises from 5 to 10% of the surface of the film containing the depressions.

12. A wound dressing as claimed in claim 1 in which the film is formed from a blend of ethylene-vinyl acetate copolymer and polysty rene.

13. A wound dressing as claimed in any one of claims 1 to 11 in which the viscous pharmaceutically acceptable carrier is an oil-in water emulsion.

14. A wound dressing as claimed in any one of claims 1 to 11 in which the pharma ceutically acceptable viscous carrier is an aqueous gel.

15. A wound dressing as claimed in any one of claims 1 to 11 in which the viscous pharmaceutically acceptable carrier is a hydro phobic ointment.

16. A wound dressing as claimed in any one of claims 1 to 15 which carries along at least one of its edges an adhesive coated handle capable of being adhered to the skin.

17. A wound dressing as claimed in claim 16 in which the dressing carries adhesive coated handles along two opposed edges.

18. A wound dressing as claimed in any one of claims 1 to 17 which is sterile and is packaged in a bacteria-proof and waterproof pack.

Published 1988 at The Patent Office, state House, 66/71 High Holborn, London WC 1 R 4TP. Further copies may be obtained from Te Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD.

Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.